I saw the article, and it looks fairly simple to build. The 6550 is a good sounding tube, although I have only heard it in push-pull. My old Quicksilver Silver Monos used 6550 B3 from Svetlana, and sounded a lot like a single ended triode amp.
I recently came across a used set of Doc Bottlehead 2a3 Paramours at a good price, and am now a firm believer in SET'S. After listening to these amps, I have decided to do Eric Barbours "single ended glory" 45 tube amp, which is also simple looking.
I just blew my last spare few hundred bucks on some 45 tubes, a Hammond chassis, the chokes, power trannie, etc. Need to get the opt's, and some passive components, and put it all together.
mg16

I have built this amplifier,and with modification on the driver section i.e. use the 2 sections of the 6sn7,it now sounds wonderful.If you desire,you can access a thread or two by looking at``6550 single-ended amplifier``on this forum.If you haven`t already...